This invention relates to optical fiber networks and methods of configuring the same, and more particularly to such networks including splitters.
Optical fiber networks are increasingly being installed to support high speed voice and data communications. Increasingly, the optical fiber coupling is being expanded out from the central office of the communication service provider companies, such as Regional Bell Operating Companies (RBOCs) to the subscriber locations, such as homes or businesses, where conventional copper wiring was conventionally used. One type of network architecture used for such networks is a centralized splitter network architecture.
FIG. 1 illustrates the components typically used in a conventional centralized splitter network architecture. These networks generally utilize electronics and lasers located in the Central Office (CO) 100 to provide service to multiple customers over a single fiber. The fiber 102 leaving the CO 100 is typically routed to a geographically convenient point near the customer service area. The signal at this point is then generally routed through an optical splitter 106, shown in a centralized splitter cabinet (CSX2) 105 in FIG. 1. The optical splitter 106 converts each input fiber into “n” number of active fibers. Splitters are typically referred to as 1×n where “n” represents the number of output fibers or “ports.” Each output port of the splitter 106 may be terminated with a connector and can provide full service to a subscriber (i.e., a customer (or potential customer) who has signed up for service from the provider). Splitters are typically added in pairs (two 1×32 splitters) due to the fact that each input fiber is typically spliced (a procedure that generally requires set up and a higher skilled technician than is usually required for general service)
With two 1×32 splitters, 64 active ports are available for assignment. These ports are referred to as stranded until subscribers take service and are coupled to the ports. Thus, with only one subscriber on the network, 63 ports are stranded. This process, of connecting customers as subscribers, typically occurs at a cabinet, shown as a centralized splitter cabinet 105 in FIG. 2 (also referred to herein as an optical splitter cabinet) that incorporates a connector field 108 (an array of connectorised fibers that permit easy mating, de-mating and reassignment of fibers via pigtails) sufficiently sized to provide each prospective customer a fiber optic connection point. This architecture generally requires a great deal of engineering to determine the maximum number of potential and future customers, such that day 1 (initial install of cable) a distribution cable with a ratio of 1 fiber to 1 customer (i.e., potential subscriber) may be placed. To accommodate unknown/unexpected expansion, extra fiber is usually placed as well. Thus, from the cabinet onward, one future customer equals one fiber in the distribution network.
The optical splitter cabinet's connector field 108 generally allows for efficient utilization of the high dollar CO equipment by provisioning service (i.e., coupling to the CO equipment) only to those customers that have subscribed for service. The optical signal leaving the cabinet 105 in such network architectures typically runs uninterrupted via the distribution network directly to the subscriber's premises. FIG. 1 illustrates a typical customer area of 288 access points available from a single centralized splitter cabinet 105 (it will be understood that additional centralized splitter cabinets 105 may also be coupled through the central office 100 and that a network may include more than one central office 100). Using the 288 point example, the distribution side of the typical conventional network has 288 fibers exiting the cabinet 105.
The cable exiting the cabinet 105 would typically be spliced into several smaller cables via a branching closure 110. The branching closure 110 is an aggregation point for multiple cables in the distribution network. The total fiber count does not generally change at the branching closure 110. The example in FIG. 1 evenly distributes the fibers between four cables (72 fibers each) running North, South, East and West. The 72 count fiber cables utilize distribution closures 115a, 115b, 115c to splice in optical distribution terminals (OTDs) 120a, 120b, 120c along their paths. The terminals 120a, 120b, 120c are typically placed “Day 1” and provide drop fibers to pockets of potential customers (N). Terminals 120a, 120b, 120c usually have 4 or 8 fibers or associated connector ports with “N” equaling the number of potential customers per terminal 120a, 120b, 120c. Thus, the number of active fibers decreases by “N” after each terminal 120a, 120b, 120c. Thus, after passing only distribution closures 115a, 115b, one having an associated 4 port terminal 120a and one having an associated 8 port terminal 120b, only 60 fibers of the original 72 in the distribution cable remain available for terminal assignment. Note that a 72 (or more) fiber optical fiber cable may be used for the entire run, with the number of those fibers coupled all the way back to the centralized splitter cabinet 105 progressively decreasing. Based on this conventional architecture, each time a subscriber is added to the network, a technician must typically visit both the centralized splitter cabinet 105 and a terminal 120a, 120b, 120c coupled to a distribution closure 115a, 115b, 115c proximate the customer to provision service (properly route the light from the CO 100 through the splitter 106 in the centralized splitter cabinet 105 to the subscriber's premises).